A tendency warning sits at the end of a long chain of procedural steps. By the time a judge delivers it, the court has already ruled that tendency evidence is admissible, directed the jury on the limited purpose of that evidence, and is now summing up. The warning is the final guardrail. It tells the jury, in plain terms, what they cannot do with what they have heard about the accused person's past conduct.
What a tendency warning actually does
The warning performs a different function from a tendency direction, even though both deal with the same evidence. A tendency direction is given when the evidence is first received by the jury. The warning comes during the judge's summing-up, just before the jury retires to deliberate. Its job is to remind jurors, at the critical moment, that tendency evidence carries a specific and confined use.
In practical terms, the warning will tell the jury three things. First, that the evidence of past conduct was received only to show a tendency, not to prove guilt by association. Second, that the jury must not reason that because the accused behaved in a certain way before, they are the kind of person who would commit the offence charged. Third, that the evidence cannot be used to reason that because the accused did something similar once, they probably did it again this time.
That last prohibition is critical. It is the propensity reasoning trap, and it is exactly what tendency evidence is designed to avoid. A judge who fails to warn against it leaves the verdict vulnerable.
When does a judge have to give one?
The obligation arises whenever tendency evidence has been admitted and placed before the jury. It is not discretionary. Once the evidence is in, the warning follows as a matter of course during the summing-up. The only real question is how detailed the warning needs to be, and that depends on how the tendency evidence was actually used at trial.
If the tendency evidence was central to the prosecution's case, the warning needs to be more precise. The judge should identify the specific evidence that carries tendency reasoning, explain the tendency it was admitted to prove, and then spell out the prohibited uses. A generic warning that tendency evidence "should be treated carefully" won't do that job.
Where tendency evidence was admitted on the application of the defence (which can happen when the defence wants to rely on consistent past conduct to support credibility), the warning adjusts accordingly. It's the same structural obligation, applied to a different factual scenario.
How it differs from a propensity direction
The two are sometimes confused because they both address reasoning from past conduct. A propensity direction deals with evidence admitted to show a general disposition toward a type of offending. A tendency warning is narrower: it accompanies tendency evidence specifically, which must be directed at a particular tendency relevant to the offence charged.
Tendency evidence requires the court to identify a specific tendency. For example, a tendency to use a particular method, or a tendency to behave in a specific way toward a particular type of person. The warning maps onto that identified tendency. It reminds the jury that the evidence goes only to that tendency, and no further.
A propensity direction, by contrast, can arise even without a formal tendency notice process. It applies when the jury has heard conduct evidence that goes to disposition more broadly. Courts in New South Wales operate under the Evidence Act 1995 (NSW), and the distinction between tendency and propensity reasoning is one the statute draws carefully.
What happens if the warning is inadequate or omitted
An omitted or deficient tendency warning can ground an appeal against conviction. The argument runs that the jury was left free to reason in a way the law does not permit. Whether that produces a successful appeal depends on whether the misdirection caused a substantial miscarriage of justice.
Courts assess this by asking whether a properly warned jury could still have reached the same verdict on the admissible evidence. If the tendency evidence was only a minor thread in a strong prosecution case, an inadequate warning may not be enough to overturn the result. But where tendency evidence was the centrepiece of the prosecution's argument, a missing warning is a serious problem.
Defence lawyers who identify an inadequate warning during the summing-up should raise it with the trial judge immediately, before the jury retires. A prompt objection gives the judge the opportunity to correct the summing-up. Failing to object at that point can complicate an appeal, even if the ground is otherwise sound.
The relationship with the tendency notice process
A tendency warning can only be given in respect of evidence that was properly admitted. That means the notice requirements, the admissibility ruling, and the tendency direction all sit upstream of the warning. A defect at any earlier stage affects the validity of what follows.
If tendency evidence was admitted without a proper ruling on its probative value, the warning becomes harder to calibrate, because the judge cannot explain the purpose of evidence that was never clearly defined. That is why the full procedural chain matters. The warning is the last step, but it only functions correctly when the earlier steps were taken properly.
Defendants facing tendency evidence at trial need advice from a lawyer who understands all of these procedural stages, not just the admissibility question. The warning is one safeguard among several, and its effectiveness depends on the work done earlier in the proceeding.
Ann Valos Criminal Law acts for defendants in matters involving tendency evidence across all stages of the proceeding, from the initial notice through to summing-up review and appeal.